Mike Moss is one of the few soda jerks who knows what a customer means when he hollers, "Shoot me a Waco!" Sure, it's a small city along Interstate 35, about halfway between Dallas and Austin, but for folks in the know, it's where the soda pop that Texans knew as Waco was created.

In 1885, a local pharmacist, Charles Alderton, invented the beverage at Morrison's Old Corner Drug Store. His taste treat — a mix of his secret syrup and carbonated water — was an instant success locally. Wade Morrison, the store owner, is credited with changing the drink's name from Waco to Dr Pepper — the period was dropped in the 1950s — who, some say, was the father of a girl he once loved.

The drugstore is long gone, but a life-size animatronic re-creation of its pharmacist greets visitors after they enter the Dr Pepper Museum, housed in an old red-brick bottling plant in downtown Waco. The drink was made and bottled here from 1906 until 1965, when the popularity of cans made the plant obsolete.

On the building's three floors, guests can view tens of thousands of soft-drink artifacts not only from Dr Pepper but also from other brands, including more obscure ones such as Kickapoo Joy Juice. Besides old bottling machines and delivery trucks, the museum features exhibits that pay tribute to good ol' capitalism.

"The educational mission of the museum is free enterprise," said Jack McKinney, the museum's director. "The American system allowed [Dr Pepper bottlers] to grow into big businesses and products. If children are taught that they can invent things and take them to market, innovation will remain strong."

McKinney spoke about the nation's oldest major soft drink — Coca-Cola came along one year later — and free enterprise on a hot and humid morning while sitting at his desk sipping a Diet Dr Pepper. He swears it's the only soda he drinks.

"I was born and raised in Dallas," he said. "I've drunk Dr Pepper since Day One"

Although sold internationally, Dr Pepper remains true to its Texas roots, with corporate offices in Plano.

"It's very popular here and in Oklahoma and Arkansas," McKinney said. "It runs neck and neck with Coke in many markets."

So what makes Dr Pepper stand out? McKinney and its consumers agree that it's the unique combination of ingredients, which remains a closely guarded secret.

"There's 23 different flavors in there," McKinney said. There's no cola in it, nor is there prune juice — a rumor competitors used to spread.

Old advertisements promoted the drink with slogans such as: "Vim, Vigor and Vitality," "Just What the Doctor Ordered" and "Drink a Bite to Eat at 10, 2 and 4."

"By about 10 a.m., your blood sugar started to fall. It pepped you up," McKinney said. He pointed out that caffeine wasn't added until the 1920s.

After exiting the exhibits, thirsty visitors make their way to the soda fountain, where museum employees mix Dr Pepper just as it was done 126 years ago, blending the thick, brown syrup with carbonated water.